It seems that almost every year the debate about whether mixing butter and oil in your saute pan increases the smoke point of the butter rears it's contentious head. Let's put this to rest. Butter has solids in it that will burn. And they will burn regardless of whether or not anything else is in the pan with it. I get this. Oil does not magically improve the cooking scenario.
But, after taking some time to observe how butter behaves in a pan versus how the combination of butter and oil work together, I witnessed some neat stuff. More often than not, butter will be cold and oil is at room temperature. A blend of cold butter and room temperature oil will heat up more quickly than an equal amount of cold butter. I set a stop watch and this proved true, but not by much. And how often are we timing our fats? The second startling observation is that the solids in the pan with all butter begin to brown first. In 12 seconds we were smelling and seeing butter solids browning. There are more solids in the pan and as the pan heats, the butter melts quickly on its own, and the milk solids are quickly released and begin to brown. In the pan with the oil and the butter, the solids are diluted by the oil and there are less of them available to begin browning. It took 25 seconds for us to see and smell butter solids browning in the pan with mixed fats. The perception is the combination of fats gives the butter a high smoke point because the solids brown more slowly. In fact, both pans were at the same temperature, 200°C. when the butter solids hit their full on smoke point and began to burn.
What is even more exciting is the extrapolations that arise from these observations. Browning butter smells amazing. We should cook with it often. Butter solids burn. Oil allows for a more free flowing fat that is liquid at room temperature. We need to separate and combine ideas based on use. The easiest is to make ghee, butter that is browned and then clarified by straining out the solids. This flavorful fat has an extremely high smoke point, 250°C. When you make it yourself, as we do, you can add those reserved solids back to your dish at the very end. We also make browned butter oil by toasting milk solids in olive oil and removing them prior to actual cooking. We can brown milk solids on their own, cook whatever we want on its own, and then sprinkle the toasted solids onto the cooked food so that rich caramelized flavor is added when we want it. Possibilities presented by curious observations.